Acoustic interferometer

About: Acoustic interferometer is a research topic. Over the lifetime, 1493 publications have been published within this topic receiving 19355 citations.

Solid-state acoustic metamaterial and method of using same to focus sound

Abstract: A phonemic crystal is made of a first solid medium having a first density and a substantially periodic array of structures disposed in the first medium, the structures being made of a second solid medium having a second density different from the first density. The first medium has a speed of propagation of longitudinal sound waves and a speed of propagation of transverse sound waves, the speed of propagation of longitudinal sound waves being approximately that of a fluid, and the speed of the propagation of transverse sound waves being smaller than the speed of propagation of longitudinal sound waves.

Acoustic effects caused by high-intensity internal waves in a shelf zone

Abstract: The sound field fluctuations caused by high-intensity, solitonlike, quasi-plane internal waves crossing a fixed acoustic path at different angles are numerically modeled for natural conditions of the shelf zone of the Sea of Japan The horizontal refraction of sound is considered for the case of an acoustic path parallel to the internal wave front

Direct experimental investigations of acoustic modes guided by a solid–solid interface using optical interferometry

Abstract: This paper presents direct field measurements of acoustic modes guided by the interface between two transparent solids. The measurement technique is based on the acousto-optical interaction inside the solid between the acoustic field and the probe laser beam of an interferometer. The main advantage of the method is its ability to measure acoustic strain fields in areas of difficult access with the classic detection methods. Moreover, it gives complete information about the dilatation strain field inside the solid, e.g., amplitude and phase. The propagation of a real velocity mode (Stoneley wave) is first illustrated. Then the situation of complex velocity modes is investigated for a Plexiglas–fused quartz slip interface. This material combination supports two possible interface modes theoretically. These modes are simultaneously observed and the differences between their behavior are measured.

Reduced acoustic cloaks based on temperature gradients

Abstract: This letter presents the design of a reduced acoustic cloak that uses a temperature gradient in order to obtain sound speeds larger than in air. The cloak consists of a circular acoustic crystal made of ten concentric layers of rigid cylinders whose surfaces are heated or cooled in order to get the temperature gradient needed for cloaking behavior. The total pressure field produced by the scattering of sound waves impinging this complex structure is computed and it is shown how acoustic waves are bent in a way similar to that predicted for perfect cloaking devices.

Ultrasonic Speeds in Compressed Liquid and Vapor Pressures for 1,1,1,2-Tetrafluoroethane

Abstract: Ultrasonic speeds in the liquid phase of 1,1,1,2-tetrafluoroethane (CF{sub 3}CH{sub 2}F) have been measured from 243.11 K to 333.15 K and from near the saturation line to about 30 MPa. The measurements were made using a sing-around technique employing a fixed path acoustic interferometer operated at a frequency of 2 MHz. The probable uncertainty in the results was no greater than {+-}0.2% except in the low-density region at near the saturation line at higher temperatures. The vapor pressures have also been observed to within {+-}10 kPa by monitoring the acoustic signal at vapor-liquid equilibrium. When these results were combined, the ultrasonic speeds for the saturated liquid were estimated to within {+-}1 m/s.